The answer to this is no. The character that Morgan Freeman plays in this movie was not a real person. Morgan Freeman plays a character named Theodore Joadson in this film. The character, in the film, is portrayed as a leading abolitionist (he is a freed slave) in the film. There was never any such person.
This is not uncommon in films that are based on historical events. Writers tend to create characters when there are not any real life characters who embody the ideas or characteristics that the writers want to show. This is one of those cases.